The invention relates to means of stringing trolley wires and more particularly to an improved means of resiliently supporting an overhead line having a lengthwise rigid structure.
In recent years, there has been remarkably developed means of resiliently supporting an overhead line of a length-wise rigid structure in place of a catenary suspension system as a laying system of trolley wires in a railway tunnel due to the fact that trolley wires must be laid in a limited laying area therein.
The means as set forth above, which resiliently supports an overhead line of a lengthwise rigid structure, mainly comprises a supporting portion, resilient portions and a sliding portion. The supporting portion is fixed to insulators installed at the inner surface of a tunnel and each of the resilient portions is held by the supporting portion to provide an overhead line with a vertical resiliency while the sliding portion is constructed to be rigid and supported by the resilient portions thereby providing the overhead line which is resiliently supported through the resilient portions by the supporting portion.
According to the resiliently supported rigid overhead line in the prior art as set forth above, each of the resilient portions is effectively adapted to accommodate the uneven contact pressure of a pantograph against the sliding portion when the pantograph moves vertically in the contact thereof with the sliding portion during the running of a train. This allows the stable collecting of electrical current for a pantograph even though a train runs in a high speed as recently prevailed. Further, the entire means is possible to be made smaller because no catenary suspension is necessary.
However, it should be noted that the contact conductor of the sliding portion is constructed of a plurality of rigid conductor units of a predetermined length along the overhead line for the mechanical reason that the sliding portion is required to have rigidity necessary to endure the pushing-up force of a pantograph.
Accordingly, there has been a drawback in the conventional means that a pantograph has the tendency of separating from the contact conductor at the joint portions of the conductor units. Further, it has been observed that the separation of a pantograph is aggravated upon the sliding portion affected by the transverse component of the thrusting force of the pantograph. That is, the resilient portions do not work properly to provide the sliding portion with the vertical resilient movement because the pantograph generates the transverse movement in the contact conductor in addition to the vertical movement which is regularly resulted from the pushing-up force of the pantograph of a high speed train. In addition, the malfunction of the resilient portions is caused by the thermal expansion and shrinkage of the contact conductor.
Conventionally, there has been otherwise proposed a system wherein a long trolley wire is clamped by a pair of long ears to provide a jointless overhead line in a long distance section whereby the separation of a pantograph from the contact conductor is eliminated. However, the long trolley wire expands and shrinks thermally proportional to the length thereof so that it is inevitable that the resilient portions are badly affected to such a greater extent that they do not work properly.
Accordingly, it is a main object of the present invention to provide means of stringing trolley wires wherein the number of joints of a sliding portion is sharply decreased thereby to result in a better characteristic for a pantograph of making a contact with the sliding portion in the high speed collecting of electrical current.
It is another object of the present invention to provide means of stringing trolley wires wherein resilient portions are perfectly excluded from the influence of the thermal expansion and shrinkage of a contact conductor.